Experimental and numerical studies on enhanced flow boiling in tube with superwetting micro-finned surfaces

Abstract

Due to the high latent heat from evaporation, flow boiling has been applied in a variety of industrial applications. However, the occurrence of “annular bubble” will dramatically increase the thermal resistance near the wall, causing decreases both in heat transfer coefficient (HTC) and critical heat flux (CHF). To tackle this issue, we propose the micro-finned surfaces with strong capillary force to enhance the heat transfer coefficient and critical heat flux for flow boiling. With deionized water as the coolant, we investigate the effects of fin width, fin height, fin pitch, coolant flow rate and heat flux on flow boiling through experiment and numerical simulation. The results show that the wider the fin width, the lower the fin height, and the smaller the fin pitch, the higher the convective heat transfer coefficient. In addition, the higher the coolant flow rate leads to higher heat transfer coefficient and lower flow boiling instability. When the heat flux increases, the convective heat transfer coefficient and flow instability increase. Among them, the microchannel with fin width of 20 μm, fin height 40 μm, and fin pitch 40 μm obtains the maximum convective heat transfer coefficient, 59.3 % higher than that of the smooth microchannel.